Method of making rubber wheels



May-28, 1946. J. B. BENNETT ErAL y v2,400,973

METHOD OF MAKING RUBBER WHEELS` original Filed Nov. 5, 1945 4C 40 Snvventers JAMES a. BENNETT 4| 4l JOHN J. MccARTER r i (Ittorneg iency, suchas rubber wheels,

a tail wheel having manner to cause early Patented May 28, 17946 .UNITED STATE METHOD oF MAKING kunnen WHEELS Jamesv B'.

Bennett, Les Angeles, nna Jenn J.

' McCarter, Alhambra, Calif., anlxnors, by mesne ents, N. J., a corporation to Thermoid Company, Trenton, of Delaware nppiientinn Nnvennbeis, 194s, serial No.'

508,791. 1944, Serial No.

to wheels having resiland relates in par- This invention relates Divided and scissor/ i v claims. (o1. 15a-'12,).

ticular to the making of a wheel having especial utility as 'a tail wheel for aircraft by reason of its exceptional durability.

'Ihe present application is a division of our accompanying application Serial No. 508,791, filed November 3, 1943 for Rubber wheel.

Although this method may be employed for making wheels having other uses, for example,

as a Wheel or roller for trucks and the like, an

object of the present invention is to provide a method for making a tail Wheel foraircraft which is capable of giving satisfactory service over a long period Yof use, as compared tothe service now being obtained from rubber-tired tail wheels. Serious difficulty is nowbeing encountered in the use of tail wheels adopted as standard equipment on` small aircraft. The severe conditions of service to which these tail wheels are subjected causes them to break down in rela.- tively short periods of replacement is necessary. In may instances it has been found necessary to remove and replace a tail wheel after it has made only one landing on the deck of an aircraft carrier. Our present invention constitutes an important contribution for the reason that it eliminates Vthe unsatisfactory condition expressed in the foregoing.

In keeping with the foregoing, it is an object of the invention to providea method for-makits parts in such cooperative relation that a durability is achieved which will make possible a minimum number of landings from a wheel ordinarily considerably in excess of one hundred.

When an aircraft lands at a speed of 75 miles per hour, a six-inch tail wheel thereon is caused to revolve at a velocity of over 4000 revolutions per minute. This means that each portion of the periphery is deformed, often under heavy loading, with such rapiditythat heat is generated within the rubber and stresses are applied which tend to disintegrate the rubber and tear it looose from its supporting wheel or hub.v This is the reason that attempts to use wheels with solid rubber tires or pneumatic tires have failed, as only relatively few landings can be made with such wheels before it becomes necessary to replace the wheel.

It is an object of this invention to provide a method for making a solid rubber tail wheel in time so that frequent this application July 31,'

one manner of explanation. the present invention may be described as a method for making a tail wheel, the 'greater .portion ot which comprises elastic material which is disposed in such a way that the shock of deformation when the' wheel is actively in use is absorbed without overworking of the rubber.

AV further object of the a method for making a tail wheel formed substantlally entirely of rubber, with side members to guide or support the side faces of the rubber wheel,` these supporting members being characterized by their ability to permit lateral expansion or ow oi' the rubber, or, in other words, a breathing of the rubber in lateral direction, during u se of the wheel in making a landing.

A further object of the invention is to provide a method for making a tail wheel, substantially of rubber, with reenforcing elements at 4the sides thereof which have locking engagement witha portion of the rubber in the wheel so'as to limit and control outward movement thereof, 'without preventing ample deformation 'of the rubber to avoid over-working and rapid failure such as referre dto in the foregoing.

A further object of the invention is to provide a method for making a tail wheel having an inner supporting member with radial walls or flanges defining an annular channel, and an annular body of rubber molded in place in this channel so as to be bonded to the walls forming the channel, with means for locking the annular body of rubber in the channel, yet permitting deformation or working of the rubber to such extent that a long period of operation of the tail which the unit deformation' of the rubber entering therein is decreased, and the deformation is distributed to such an extentv that 'even at high speed rotation in contact with an landing deck or field, the rubber will not be over-worked in a failure of the wheel. In

wheel is achieved.

A further object of the invention is'to provide a method of making a wheel of the character described wherein the supporting structure of the wheeL provides an annular channel with bars extending across this channel spaced from the bottom of the channel, with a rubber body of annular form, having an inner annular portion and an outer annular portion lying respectively within and outside the space defined by the bars, and being bonded together in the spaces between the bars. A further object of the invention is to provide a process for making a wheel ofthe character described wherein the rubber body comprises circular laminations of relatively thin or slender rubber material having its grain structui'e running circumferentially, consecutive laminations being bonded together and cured in place. A further object of the invention is to provide a method for making a tail wheel of the character set forth in the preceding two paragraphs wherein the laminationsor wraps of rubber adjacent -the bars flow or curve around the bars invention is to provide the character described is as follows: The wheel hub 9 is supportedfor rotation adjacent a device 28, Fig. 3, for forming a long slender rubber element suitable for winding in the channel 2| of the hub 9. For this purpose we have diagram- Fig. 3 isa schematic view showing the manner in which the rubber is formed initially into an approximate annular body.

Fig. 4 is a fragmentary sectional view showing the manner thevbars are applied after the rubber is initially placed. Fig. 5 is an enlarged fragmentary section showing the manner in which the lamina of rubber flow or curve around a cross bar of the wheel structure.

. In the drawing the wheel 5 illustrated has'a form in which it is suited for use as a tail wheel for an aircraft. When so used, the wheel 5 is a tubular metal wall I5 cooperating so as to form a hub in which anti-friction bearings I9 support the wheel 5 for rotation on the axle I I, there being grease seals at the ends of the tubular wall portion I5.

The inner tubular wall portion I5 and the flanges I3 define an annular channel 2l. In the flanges I3 there are aligned openings 22 and 23 arranged .so as to define a circle, and being spaced outward from the bottom of the channel 2|. The openings 22 and 23 are disposed in alternate order, and the outer ends of these openings are countersunk or flared as shown. Through the openings 22 pins 24 are extended, these pins projecting through the annular rubber body I0 and having the ends thereof expanded so as to be connected to the flanges I3 in a manner to resist separation of the flanges I3.

The pins 24 are placed on a circular li'ne or' cylindric surface which divides'the rubber body IIJ into an inner portion 25 and an outer portion 26, this outer annular portion 26 of the body I0 projecting beyond the periphery of the vflanges I3 so as to provide a rubber tread 21' for the wheel, which tread is supported in the wheel structure on an annular mass of rubber having considerable thickness, and therefore ample ability as a cushion to absorb the shocks received by the tread. Thepins or bars 24 lock the rub-v ber body II) in the channel 2| and also prevent sliding of the rubber body I0 in the channel or rotation of the body I0 relatively to the vmetal support which forms the channel 2|. The inner annular portion 25 of the rubber body I0 is,`how

ever, connected to the outer annular portion 26 matically shown the device 28 as comprising a.

calender having rollers 29, 30, and 3I. In the' operation of the device 28 a strip or strand of rubber 32 is fed forward, and this is wound in a continuous spiral in the channel 2`I of the hub 9, as shown in Fig. 3. The normal tension exerted in the rubber element 32 in the ordinary process of winding the same causes each turn of the spiral to be pulled tightly down against the preceding turn, and since each succeeding turn is under tension, the interior portion of the mass j of rubber wound on the spool or hub 9 is under compression, which, however, is slight.

The rubber element 32 is ordinarily in the form of a flat band or ribbon, and the Width of this ribbon is varied in accordance with the variations in the width of the channel 2|, and then after the channel 2| is completelylledl with raw rubber compound by this Winding process, the strip is widened and the winding process is'continued for the purpose of applying an external band of rubber which will enter into the formation of the tread 21. The foregoing is illustratedA in Fig. 4 which shows laminations of uncured rubber compound ribbon 33 substantially filling the channel 2I with wider laminations I34 externally disposed to provide tread stock.

After the crude rubber is wound in place, the unit thus formed is weighed so as -to check on the amount of rubber. The amount of rubber ordinarily applied in the winding process is generally slightly in excess of the requirement so that a surplus of rubber will be provided which may be trimmed down to give the required weight of rubber stock. The unit, as shown in Fig. 4, is then placed inside a metal ring 35 and the pins 24 are applied. It will be noted that these pins 24 have axial openings, and, as shown in Fig. 4, the stem 36 of a spear 31 is projected into the opening of a pin 24, and then downward force is applied to move the spear downward from the position in which it is shown in Fig. 4 through one of the openings 22, then through the uncured rubber occupying the `channel 2l, and finally through the aligned lower opening 22, the pin 24I following the spear so that when the spear is withdrawn after itis passed through the lower opening 22, the pin 24 will be left in place and may be later headed or expanded at the ends so as to have the form thereof shown in Fig. 2. Rubber cement is ordinarily applied first to the spear and to the pin 24, which rubber cement will serves as a lubricant. action of the spear 31 is to separate the lamina- 'tions so that the portions thereof adjacent the pins 24 will ow or curve around the outer surfaces of the pins 24 as shown at 38 in Fig. 5. The rubber layers at this point being considerably elongated mayl be thinned out to such an extent that it is difficult to illustrate in Fig. 5. The laminations which enter into the inner and outer portions 25 and 26 of the rubber body I0 are bonded together in the spaces between the pins 24 as shown at 39 in Fig. 5. By reason of the process employed, the grain in the rubber in the annular body Ill extends substantially ciroularly around the axis of the rotation of the wheel, and in the rubber body I 0 greaty durability is u achieved.

As shown in Fig. 5, the

`eriesorsaidiiangessoas to through said openingsin curing said vrubber After placement of the pins 2l as illustrated in Fig. 4, the ends oi the pins are ilared, and the unit is then placed in a mold and cured underv heavy pressure. thereby producing a homogeneous rubber body HI and forcing portions or the rubber out through the openings 23 so astonll the same. l

ate with annular beads 4|.'which project in-` wardly from the flanges I3 near the peripheries thereof, in locking the rubber body l0 in the channel of the hub v9. The openings 23 also provide ror a lateral breathing or expansion or the rubber of the body l0 when compressive forces are radially applied. This is particularly desirable where the load on the wheel is suddenly applied when the airplane carrying it lands on a deck or a runway. v

Other embodiments or the invention may be resorted to without departing from the spirit of the invention.

We claim as our invention:

l. A method of making a wheel having a resilient body which includes: wrapping a band of elastic material around a rigid wheel-hub in the medial plane of the hub, effecting connection of the wraps to each other to rintegrate them into a solid body, and providing openings in the flanges into which the elastic body may expand to ref lieve the compression stresses in the resilient body that may be developed therein by a suddenly applied load.

2. The method or making a rubber wheel having an inner supporting means ,with radial walls defining an outwardly faced annular channel.

said-radial walls having aligned openings therein spaced outwardly from the bottom oi said channel, comprising: winding spirally in said channel an uncured rubber strand having a longitudinal grain underV tension in said channel from the4 Vbottom outward so asto ll the same and continuing said winding radially beyond the peripheries or said anges so as to providel stock for a tread for the whee passing a pointed member through said openings in said radial walls and through therubber wound in said channel to separate the turns of the rubber strand and rollowing said pointed member with a pin; expanding the ends or said pins so thatlsaid pins will tie said radial wall together; and curing said rubber while the peripheral portion thereof is in a mold to form the projecting portion ot the rubber into a tread. l

3. The method or making a rubber wheel having an inner supporting means with radial walls defining an outwardly faced annular channel, said radial walls having aligned openings therein spaced outwardly from the bottom or said channel. comprising: winding spirally in said channel an uncured rubber strand having a longitudinal grain under tension in said channel from the bottom outward so as to nll the same and continuing saidwinding radially beyond the periphprovide stock for a tread for the wheel: a pointed member i said radial walls and through the rubber wound separate the turns or the rubber strand and iollowing said pointed member with a pin: and while the peripheral portion thereof is in a mold to form the projecting portion oi.' the rubber into a :i`

a. Themetbod or making a rubber r :f i.: :f:

in said channel to` ing an inner supporting means with radial walls said radial walls having aligned openings therein spaced outwardly from the bottom of said channel, including: winding spirally in said channel an uncured band of vulcanizable rubber in said channel from the bottom outwardly so as to fill the same and continuing said winding radially beyond the periphery of said ilanges so as'to pro- -vide stock for a tread for the wheel; passing a pointed member through said openings in said -radial walls and between layers of said band of rubber and following said pointed member with a pin securing said pin to said anges; and curing said rubber while the peripheral portion thereof is in a mold to form the projecting portion of the rubber into a tread.

5. The method or making a rubber wheel hav- I ing an inner supporting means with radial walls defining an outwardly faced annular channel, said radial walls having aligned openings therein spaced outwardly from the bottom of said channel, including: Winding spirally in said channel an Auncured band of vulcanizable rubber in said channel from the bottom outwardly so as to fill the same and continuing said winding radially beyond the periphery or said flanges so as to .provide stock for a tread for the wheel; passing a pin through said openings in said radiali walls and between layers of said wound band or rubber; securing said pin to said radial walls; and curing said rubber while the peripheral portion is in a mold to cause it to be formed into a homogeneous body of rubber and to form the projecting portion of the rubber into a tread. 6. The method of making a rubber wheel having an inner supporting means with radial walls dening an outwardly faced annular channel. including: winding spirally in said channel an uncured band of vulcanizable Irubber in said channel from the bottom outwardly vso as to fill the same and continuing said winding radially beyond the periphery of said flanges so as to provide stock for a tread for the wheel; separating adjacent layers of said wound band of rubber to provide a. space; passing a .pin through said space between said layers; securing said pin to said radial walls; and curing said rubber while the peripheral portion is in a mold to,eause it to be formed into a homogeneous body or rubber and to rorm the projecting portion of the rubber into a tread. y 7. The method of making a rubber wheel having an innersupporting means with radial walls deiining an outwardly raced annular channel, including: winding spirally in said channel an uncured band of vulcanizable rubber in said channel from the bottom outwardly so as to nll the same and continuing said winding radially beyond the periphery or said anges so as to provide stock for a tread for the wheel; separating adjacent layers of said wound band of rubber to provide a space; passing a pin through said space between said layers; securing said pin to said rubber andto vulcanize said body ot rubber to the walls or saidoutwardly raced annular channel and to said pin.

, JAMES B. BENNE'lC'lo JOHN J. McCAR'lEB. 

